The present invention relates to an image forming apparatus of the type transporting a paper sheet to which a visible image or toner image formed by an electrophotographic process is to be transferred from an image carrier or photoconductive element from a paper feeding section to a paper discharging section via an image transferring section and an image fixing section. More particularly, the present invention is concerned with an image forming apparatus which facilitates the removal of a paper sheet which might have jammed in a paper transport path and therefore enhances the efficient maintenance of the device.
In an electrophotographic copier, laser printer, facsimile machine or similar image forming apparatus implemented by an electrophotographic process, a toner image is formed on an image carrier such as a photoconductive element by an electrophotographic process and transferred by a transfer charger to a paper sheet which is fed from a paper feeding section. The paper sheet carrying the toner image thereon is separated from the photoconductive element, then transported to a fixing section for fixing the toner image, and then driven out of the apparatus to a paper discharging section. A paper transport path extending from the paper feeding section to the paper discharging section has not only paper transporting means and guiding means but also a transfer charger, fixing roller and other various process units. Hence, a paper sheet being moved along the transport path is apt to jam it. To facilitate the removal of a jammed sheet, it has been customary to arrange the paper transport path such that the process units can be pulled out of the apparatus body, as needed. Japanese Patent Laid-Open Publication (Kokai) No. 54-88129, for example, discloses an apparatus in which all the units constituting a paper transport path inclusive of a paper feed unit can be pulled out frontward as desired. While this kind of configuration may facilitate the removal of a jammed sheet and maintenance, it critically reduces the mechanical strength of the front end of the apparatus body because a device for pulling out all of the units is provided over the entire width of the front end. The apparatus body, therefore, has to be further increased in dimensions. In addition, the structure of the apparatus body has to be reinforced so as to prepare for the pull-out of the above-mentioned device. Moreover, when it comes to an image forming apparatus having a plurality of paper feeders arranged one upon another, such a prior art scheme does not have much effect on any paper jam which occurs at a lower paper feeder. Japanese Patent Laid-Open Publication No. 57-184943 proposes an apparatus in which a paper transport path extending from a paper feeding section to a paper discharging section is divided into two parts at, for example, a position between a transport belt for transporting a paper sheet from an image transferring section to an image fixing section and an inlet guide of the image fixing section. Process units belonging to one of such two parts and those belong to the other part can be pulled out of the apparatus away from each other in the intended direction of paper transport. With this scheme, however, it is impossible to mount a sorter, finisher or similar optional unit on the side of the apparatus body where the paper discharging section is positioned, for example. This prevents an image forming apparatus from being systematized or being provided with multiple functions.